Technical Field
The present disclosure relates to a laser welding apparatus and a laser welding method in which a butted interface or a lapped portion of a workpiece is welded by laser irradiation.
Background
Wire harnesses are often used for internal wiring of automobiles. A wire harness is a module in which a plurality of coated wires are assembled in accordance with in-vehicle wiring specifications. Terminals for connection (hereinafter referred to as crimp terminals) are crimped to ends of each of the coated wires. When connecting a crimp terminal to a wire end of the wire harness, electrical connection between the wire end and the crimp terminal is provided by stripping the insulating coating layer at a wire end to expose the core wire, and swaging and crimping a core wire barrel of the crimp terminal to the exposed portion of the core wire. The connecting portion between the crimp terminal and the wire end is sealed with resin so as to prevent corrosion of the core wire due to ingress of moisture into the wire from the connecting portion (see Japanese Laid-Open Patent Publication No. 2001-167821 and Japanese Laid-Open Patent Publication No. 2012-069449, for example).
However, sealing the connecting portion of the crimp terminal and the wire end with resin gives rise to an increase in the manufacturing cost of the wire harness. This is because, in addition to the fact that the resin used is expensive in itself, time is required to apply and cure the resin in a resin molding process or a coating process.
Thus, attempts have been made to bend the crimp portion (wire connecting portion) of the crimp terminal by pressing and to join, by laser welding, an entire butted interface between opposite ends of a plate material formed in a portion bent into a tubular shape, so that the crimp portion has a closed structure. The portion bent into a tubular shape has a tapered curved shape or a constricted curved shape at one end portion thereof (see FIG. 8). Thus, in order to join the butted interface of the portion bent into a tubular shape by laser welding, the focus of laser light needs to be moved along the butted interface.
The present disclosure is related to providing a laser welding apparatus and a laser welding method that enable laser welding of the butted interface of the workpiece with high quality.